The pickling method of purification of miropowder of silicon carbide in submicro levelAffiliated technical field
The present invention relates to the pickling method of purification of a kind of method of purification of silicon carbide ceramics micro mist, particularly a kind of miropowder of silicon carbide in submicro level.
Background technology
Miropowder of silicon carbide in submicro level is widely used in aerospace, petrochemical complex, machinery, sealing, electron trade etc.Supply falls short of demand especially for the miropowder of silicon carbide in submicro level of high purity, low impurity.And in the production in enormous quantities of silicon carbide in submicro level, be to use sand mill to grind refinement to carborundum powder, the carborundum powder of use and grinding medium all contain a large amount of impurity, consist predominantly of free silica, silicon-dioxide, iron and ferric oxide.Current purification silicon carbide micro-powder and go impurities removing method mainly to concentrate on by soda acid and wash or the problem such as by adding the method for the vitriol oil, technique is loaded down with trivial details with regard to causing for this, labour intensity large, long processing period, purification impurity-eliminating effect are relatively bad.Based on above factor, therefore a kind of technique of needs is simple, the operational cycle is short, input manpower is few, the method for purification good impurity removing effect.
Chinese patent discloses a application for a patent for invention, the title of patent application is " a kind of purifying process of silicon carbide micropowder ", application publication number CN102328929A, Shen Qing Publication day is on January 25th, 2012, this application technique is simple, but the vitriol oil used is undesirable to the removal effect of the iron and its oxi in silicon carbide micro-powder in pickling, and insulation and the reaction times long.The iron that embodiment provides and oxide content are 0.16%, and as pressureless sintering silicon carbide articles is used powder, foreign matter content is too high, affect the quality of goods after sintering.
Chinese patent discloses a application for a patent for invention, the title of patent application is " production method of high-purity carborundum micropowder ", application publication number CN101734662A, Shen Qing Publication day is on June 16th, 2010, the method of purification of the document adopts twice soda acid to wash, and its technique is more complicated, the operational cycle is longer.
Summary of the invention
The object of this invention is to provide that a kind of technique is simple, the operational cycle is short, purification good impurity removing effect, particularly on affecting the free silica of sintering quality in silicon carbide micro-powder, the pickling method of purification of the miropowder of silicon carbide in submicro level that the removal effect of iron and its oxi is good.
Technical scheme of the present invention is: a kind of pickling method of purification of miropowder of silicon carbide in submicro level, and the method comprises the following steps:
1) batch mixing: the miropowder of silicon carbide in submicro level that need are purified adds pure water, and to be configured to solid content be 40-60% slurry, puts into slurry with stirring and the pickling still of heating;
2) pickling is purified: under whipped state, in pickling still, add hydrochloric acid and nitric acid, be heated to, after 50-100 ℃, add hydrofluoric acid and be incubated after 1.5-3 hours, and remain on more than 50-100 ℃, after insulation finishes, the slurry after pickling is pumped in water washing tank;
3) washing: use the tap water after quartz sand and activated carbon filtration to wash pickling material in water washing tank, utilize PH test paper to carry out acidity detection to pickling material, when pickling material is washed to PH=4-5, with deionized water, pickling material is washed again, until during the pH value=6-7 of pickling material, the complete slurry of washing is pumped in storage tank stand-by;
4) spraying is dry: the spray-dried tower of the slurry in storage tank is sprayed dry, the inlet temperature of spray-drying tower is set in 120-450 ℃, and temperature out is set in 80-200 ℃, and dried material is finished product submicron silicon carbide micro mist.
The above-mentioned miropowder of silicon carbide in submicro level that need purify and the mass volume ratio of hydrochloric acid, nitric acid and hydrofluoric acid are 1:0.1-0.7:0.02-0.22:0.02-0.8.
The mass percent of above-mentioned hydrochloric acid is 31%-35%, and the mass percent of nitric acid is 95%-98%, and the mass percent of hydrofluoric acid is 50%-55%.
The purity of miropowder of silicon carbide in submicro level prepared by above-mentioned technique is > 99.0%, the massfraction < 0.04% of free silica, the massfraction < 0.08% of silicon-dioxide, the massfraction < 0.012% of iron and its oxi.
Technical scheme of the present invention has following characteristics: 1, technique is simple: only need just can complete acid cleaning process through a pickling; 2, the operational cycle is short: acid is added in pickling still, under the condition that stirs and heat, only need insulation can complete for 1.5-3 hour; 3, purification good impurity removing effect: after pickling, washing, miropowder of silicon carbide in submicro level purity is > 99.0%, free silica massfraction < 0.15%, silicon-dioxide quality mark < 0.15%, iron and its oxi massfraction < 0.15%, above-mentioned technical indicator is better than the index of prior art greatly; 4, acid amount is controlled: for foreign matter content different treat pickling material, can adopt different acid adding amounts, stopped to produce waste; 5, reduced cost, protection of the environment: adopted in process of production the principle of stirring, heating and insulation and produced and can all adopt pipeline to be connected, the production technique time be short, has reduced cost, and has stopped waste, has protected environment; 6, the feasibility of industrial mass production: all adopted in process of production pipeline UNICOM, metering adopts number to control, and provides guarantee to mass industrialized production; 7, labour intensity is low, has ensured safety in production: the pipeline of employing connects and the sub-volume pump of number is controlled, and has reduced labour intensity, has avoided operator directly to contact material, has ensured safety in production.
Embodiment
Embodiment 1:
1) batch mixing: the former powder of α type silicon carbide of 100Kg is added to pure water, and to be mixed with solid content be 40% slurry, by the slurry preparing pump into stir and the pickling still Free Carbon clearing device of heating in, stir and make slurry even in 4 hours;
2) pickling is purified: under whipped state, to adding mass percent in pickling still, be the nitric acid 22L that 31% hydrochloric acid 10L and mass percent are 95%, be heated to after 50 ℃, adding mass percent is 50% hydrofluoric acid 80L, about 50 ℃ insulations 3 hours, after pickling finishes, the slurry after pickling is pumped in water washing tank;
3) washing: use the tap water after quartz sand and activated carbon filtration to wash pickling material in water washing tank, utilize PH test paper to carry out acidity detection to pickling material, when pickling material is washed to PH=4 left and right, with deionized water, pickling material is washed again, until during the left and right, pH value=6 of pickling material, the complete slurry of washing is pumped in storage tank stand-by;
4) spraying is dry: the spray-dried tower of the slurry in storage tank is sprayed dry.The inlet temperature of spray-drying tower is set in 120 ℃, and temperature out is set in 80 ℃, and dried material is finished product submicron silicon carbide micro mist.
After testing, the miropowder of silicon carbide in submicro level purity after purification reaches 99.4%, and free silica is 0.04%, and silicon-dioxide is 0.08%, and iron and its oxi is 0.012%.
Embodiment 2:
1) batch mixing: the former powder of α type silicon carbide of 100Kg is added to pure water, and to be mixed with solid content be 60% slurry, by the slurry preparing pump into stir and the pickling still Free Carbon clearing device of heating in, stir and make slurry even in 2 hours;
2) pickling is purified: under whipped state, to adding mass percent in pickling still, be the nitric acid 2L that 35% hydrochloric acid 70L and mass percent are 98%, be heated to after 50 ℃, adding mass percent is 55% hydrofluoric acid 2L, about 100 ℃ insulations 1.5 hours, after pickling finishes, the slurry after pickling is pumped in water washing tank;
3) washing: use the tap water after quartz sand and activated carbon filtration to wash pickling material in water washing tank, utilize PH test paper to carry out acidity detection to pickling material, when pickling material is washed to PH=5 left and right, with deionized water, pickling material is washed again, until behind pH value=7 of pickling material, the complete slurry of washing is pumped in storage tank stand-by;
4) spraying is dry: the spray-dried tower of the slurry in storage tank is sprayed dry.The inlet temperature of spray-drying tower is set in 450 ℃, and temperature out is set in 200 ℃, and dried material is finished product submicron silicon carbide micro mist.
After testing, the miropowder of silicon carbide in submicro level purity after purification reaches 99.2%, and free silica massfraction is 0.03%, silicon-dioxide quality mark 0.07%, iron and its oxi massfraction 0.009%.
Example 3:
1) batch mixing: the former powder of α type silicon carbide of 100Kg is added to pure water, and to be mixed with solid content be 50% slurry, by the slurry preparing pump into stir and the pickling still Free Carbon clearing device of heating in, stir and make slurry even in 3 hours;
2) pickling is purified: under whipped state, to adding mass percent in pickling still, be the nitric acid 10L that 33% hydrochloric acid 40L and mass percent are 96%, be heated to after 80 ℃, adding mass percent is 53% hydrofluoric acid 40L, about 80 ℃ insulations 2 hours, after pickling finishes, the slurry after pickling is pumped in water washing tank;
3) washing: use the tap water after quartz sand and activated carbon filtration to wash pickling material in water washing tank, utilize PH test paper to carry out acidity detection to pickling material, when pickling material is washed to PH=4, with deionized water, pickling material is washed again, until behind pH value=7 of pickling material, the complete slurry of washing is pumped in storage tank stand-by;
4) spraying is dry: the spray-dried tower of the slurry in storage tank is sprayed dry.Spray-drying tower inlet temperature is set in 300 ℃, and temperature out is set in 100 ℃, and dried material is just product submicron silicon carbide micro mist.
After testing, the miropowder of silicon carbide in submicro level purity after purification reaches 99.2%, free silica massfraction 0.03%, silicon-dioxide quality mark 0.07%, iron and its oxi massfraction 0.009%.